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Many cultural heritage sites in Mexico have been built with volcanic tuff rocks from the earliest Central American civilizations to the time of the Spanish conquest and up to the present. Throughout this long period of time, the stones have been subjected to progressive weathering as evidenced by different types of damage phenomenon such as scaling, sanding, crumbling, sugaring and salt efflorescence. This study utilizes a collection of 53 tuffs from different regions in Mexico that show a diverse range of colors, rock compositions and mineralogy, and heterogeneous rock fabrics indicative of their volcanic origin. Comprehensive investigations have been done that include detailed petrographic analyses, cathodoluminescence, clay mineral analyses, and the determination of a wide range of petrophysical properties (e.g., porosity, capillary water uptake, water absorption, sorption, hydric and thermal expansion, and mechanical properties). All analyzed data combined are used for derivation of some general trends concerning the suitability/durability of tuffs applied as natural building stones.

This paper presents the petrographic and textural characterization of some ornamental limestones widely used in UNESCO World Heritage Sites in northeastern Italy, and the assessment of the main decay factors present in the environment where they are employed. Eleven carbonate building materials have been here considered, all commonly present in the built environment of northeastern Italy: two different varieties of Vicenza Stone (Nanto and Costozza), of Verona Stone (Red and Brown Verona), of Asiago Stone (Pink and White Asiago), and of Chiampo Stone (Ondagata and Paglierino), the Istria Stone (Orsera), the Aurisina Stone, and the Botticino Stone. The Carrara marble is also considered, and used as a reference material for the determination of the grain-size distribution. Stone durability was measured by accelerated aging tests which reproduced freeze–thaw and salt crystallization cycles, among the main causes of deterioration in the region. Petrographic and textural features of these carbonate rocks as well as their porosity resulted to strongly influence their deterioration rate, and their knowledge is, therefore, essential when trying to predict stone decay as a function of the local environmental forcings.

The HYPERION EU project aims to develop a Decision Support System to improve resilience and sustainable reconstruction of historic areas faced with climate change and extreme events. In this context, Venice presents an outstanding example of urban and architectural complexity and richness. The mapping of the ornamental stones of the façade of the Venice Clock Tower (Torre dell’Orologio) and their deterioration patterns acts as a milestone on which to build the knowledge-acquisition process of the system as regards stone artefacts and their decay products. The Clock Tower is an early Renaissance building (1499) in Lombardesque style and stands over the entrance to the Mercerie on the northern side of St. Mark’s Square. Detailed surveys and mapping of both building materials (mainly stones) and deterioration patterns were carried out, the latter following the glossary of weathering forms, coupled with an easy-to-use scale of evaluation of their intensity. The data output consists of several monothematic maps which can be handled separately, each one focusing on precise lithological or specific deterioration aspects. This study also proposes a simple approach to summarizing the total state of deterioration of the building in the form of a Total Deterioration Rank (TDR) and its representation. The stones used in the façade are regional (Ammonitico Rosso and Scaglia Rossa) and extra-regional limestones (Istrian Stone), as well as Mediterranean white and coloured marbles and stones already used in antiquity (i.e., Fior di Pesco or marmor chalcidicum, lapis porphyrites, a volcanic rock from the Egyptian Eastern Desert, Proconnesian marble from the Island of Marmara, Pavonazzetto toscano and white Carrara marble from the Italian Apuan Alps). The most frequent forms of deterioration detected are black crusts, patinas, discoloration and patterns linked to erosion processes. The interrelation of different mappings led to a number of useful considerations concerning differences in the effectiveness of maintenance procedures between public and private management of the monument.

The disposal of stone waste derived from the stone industry is a worldwide problem. The shortage of landfills, as well as transport costs and environmental pollution, pose a crucial problem. Additionally, as a substitute for cement that has high carbon emissions, energy consumption, and pollution, the disposal of stone wastes by utilizing solid waste-based binders as road base materials can achieve the goal of “waste for waste”. However, the mechanical properties and deterioration mechanism of solid waste-based binder solidified stone waste as a road base material under complex environments remains incompletely understood. This paper reveals the durability performance of CGF all-solid waste binder (consisting of calcium carbide residue, ground granulated blast furnace slag, and fly ash) solidified stone waste through the macro and micro properties under dry–wet and freeze–thaw cycling conditions. The results showed that the dry–wet and freeze–thaw cycles have similar patterns of impacts on the CGF and cement stone waste road base materials, i.e., the stress–strain curves and damage forms were similar in exhibiting the strain-softening type, and the unconfined compressive strengths all decreased with the number of cycles and then tended to stabilize. However, the influence of dry–wet and freeze–thaw cycles on the deterioration degree was significantly different; CGF showed excellent resistance to dry–wet cycles, whereas cement was superior in freeze–thaw resistance. The deterioration grade of CGF and cement ranged from 36.15 to 47.72% and 39.38 to 47.64%, respectively, after 12 dry–wet cycles, whereas it ranged from 57.91 to 64.48% and 36.61 to 40.00% after 12 freeze–thaw cycles, respectively. The combined use of MIP and SEM confirmed that the deterioration was due to the increase in the porosity and cracks induced by dry–wet and freeze–thaw cycles, which in turn enhanced the deterioration phenomenon. This can be ascribed to the fact that small pores occupy the largest proportion and contribute to the deterioration process, and the deterioration caused by dry–wet cycles is associated with the formation of large pores through the connection of small pores, while the freeze–thaw damage is due to the increase in medium pores that are more susceptible to water intrusion. The findings provide theoretical instruction and technical support for utilizing solid waste-based binders for solidified stone waste in road base engineering.

Predicting uniaxial compressive strength (UCS) of building stones after deterioration by freeze–thaw action is critical in selecting the stones for outdoor applications especially in cold regions. The main aim of this paper is to develop predictive models for UCS estimation of building stones after freeze–thaw action. To do this research, at first, 22 different carbonate building stones from various quarries in Iran were subjected to freeze–thaw cycles and the stone damage caused by freeze–thaw process was evaluated. Then, the effect of freeze–thaw cycles on the UCS of these stones was experimentally investigated. Afterwards, two statistical models were developed to estimate the UCS of carbonate building stones after deterioration by freeze–thaw action. These models predict the UCS of stone after freeze–thaw action employing relatively simple and low-cost tests (porosity and P-wave velocity of fresh stone). The results indicate that both proposed models can be applied to determine the UCS of construction and building stones after freeze–thaw cycles with acceptable accuracy. Furthermore, the comparison of models based on statistical performance indices shows that model 2 produces better predictions than model 1. The coefficient of determination (R2), normalized root mean square error (NRMSE), and variance account for (VAF) indices were obtained as 0.992, 0.054, and 99.259 for model 2, respectively.

Marble as ornamental and dimensional stones as well as in their natural environments show complex weathering phenomena. Physical, chemical, and biological weathering of marble are well documented. The impact of climate change on monuments and historic buildings in terms of modeling and predicting future scenarios requires new approaches to forecast the ongoing decay in the near and far future. Ultrasonic wave velocities are a powerful and sensitive tool for the damage assessment of marble. For a maximum porosity of up to 1%, ultrasonic wave velocities (P-wave velocities) are ranging between 1 km/s and over 6 km/s. Water saturation has an important influence on the magnitude and directional dependence of ultrasonic wave velocities together with the mineralogical composition and the rock fabrics. Ongoing experimental alteration approaches were used to document the state of deterioration using Vp-systematics. In addition, thermal expansion and the residual strain values after applying thermal impacts were used to introduce a new quantitative measure based on experimental length changes and volume changes. To quantify such volume changes, a so-called decay index was proposed. Marbles are sensitive to weathering and have different volume changes under exposure depending on fabric parameters. The volume extension index of marble, based on thermal expansion measurements under dry and water-saturated conditions, is proposed as a decay index for quantifying sample stability and for defining the directions of maximum and minimal dilatation. Such decay index was implemented to different marble types and it was turned out that marbles with the larger decay indexes are more prone to weathering than with smaller ones. The effect of changing climate and, in consequence, different weathering actions can help to calculate or forecast risk numbers based on the Vp data in combination with the proposed decay index especially for marbles.

Calcareous stones, such as marble and limestone, have been widely used in ancient architecture due to their durability, abundance, and ease of extraction and workability. However, their chemical nature renders them vulnerable to atmospheric pollutants. With industrialization and socio-economic growth, air pollution has severely impacted built heritage, including numerous historical buildings and monuments, particularly under changing climate and environmental conditions. Various forms of degradation, such as acid corrosion, mineral crystallization, and black crusts, are widespread and typically driven by atmospheric pollutants like sulfur dioxide (SO2), nitrogen oxides (NOX), ozone (O3), and particulates (PM), which accelerate the deterioration of stone surfaces. To develop sustainable mitigation strategies, it is essential to gain an in-depth understanding of these deterioration mechanisms and current technological advancements. This paper first reviews the influencing factors and underlying mechanisms of atmospheric deterioration of calcareous stones. Subsequently, it discusses the advantages and limitations of traditional and advanced conservation and restoration techniques at the micro-level, as well as pollution management strategies that can be adopted. Finally, the challenges of research in this field are highlighted, and directions for the sustainable conservation of calcareous stones are proposed.

This paper proposes a non-destructive approach based on the Equotip hardness tester to assess weathering deterioration in a protected sandstone monument located in the historic centre of Camerino (Italy). The approach is tested on one sandstone column, where various forms of weathering, such as discolouration, scaling and loss of stone volume, are observed. The mechanical characterisation with Equotip was performed on 24 measuring points, systematically distributed in the column. Innovatively, the two probes available from Proceq (Proceq© 2010 ) were used to assess differences among surface and in-depth hardness values of the column. In addition, an un-weathered rock core from the original extraction site was also analysed and compared with the rock matrix of the column. The obtained results show a 15% hardness reduction from depth to the surface of the column and a 25% overall hardness reduction with respect to the fresh sandstone core samples. Equotip results were coupled with grain size analyses, mercury intrusion porosimetry, scanning electron microscopy and X-ray diffractometry results, and a correlation between hardness and grain size was evaluated. By combining these approaches, it was possible to identify the processes that occurred during weathering: (a) freeze-thaw cycles that caused a decrease in micropore volume and an increase in macropores connected with low Equotip values; (b) iron oxide and sulphuric acid released from pyrite oxidation contribute to the dissolution and precipitation of calcium carbonate, which can be rearranged in the outer and surface macroporosity. The quantitative approach proposed in this study may be a valid low-cost and quick tool to assess weathering heterogeneities on building stone materials and to provide insights for effective preservation strategies of historical monuments.

Uniaxial compressive strength (UCS), which is one of the most important engineering properties of natural building blocks, exhibits a decrease at various rates under the effect of freeze–thaw (FT) cycles. In this study, practical estimation of UCS loss of 21 groups of carbonate building stones exposed to 4, 7, 10, 14, 20, 28, 35, 56, 70 and 84 FT cycles is aimed by proposed estimation models. In all models, the Leeb hardness (HLD), which is practically determined by a dynamic surface hardness test method, was used as major input parameter. Other basic stone properties and number of FT cycles were also used as additional input parameters in developed models. The test results indicated that HLD and UCS values decreased up to 13 and 40%, respectively, at the end of 84 FT cycles. Proposed equations are reliable and beneficial in estimation of deteriorated UCS values of carbonate building stones in practical engineering applications and scientific studies.